CN103765292B - Eyepiece system and image observation device - Google Patents

Abstract

Realizes an eyepiece system that can perform excellent aberration correction with good telecentricity on the object side. It is an eyepiece system that magnifies and forms the image of the observed object as a virtual image. It has the first group G1 with negative refractive power arranged on the side of the image display element, and the second group G1 with positive refractive power arranged on the eyeball side of the first group. Group G2, the first group is a cemented lens of biconcave lens and biconvex lens, and the second group G2 is composed of two or three positive lenses, which are telecentric on the object side and satisfy conditions (1) and (2).

Description

Eyepiece system and image observation device

technical field

The present invention relates to an eyepiece system and an image observation device.

Background technique

An eyepiece system that magnifies an object image as a virtual image has been widely used in various optical devices such as loupes and microscopes.

Alternatively, the following operation is also performed: imaging the object-side end face of the "image transmission body using an optical fiber bundle" of the endoscope, transmitting the image to the eye-connecting end face of the optical fiber bundle, and transferring the transmitted image to the end face of the optical fiber bundle. The image is used as the observation object, and the eyepiece system is used as a virtual image to magnify the observation.

Moreover, in recent years, there has also been an operation of two-dimensionally displaying video contents such as virtual reality, movies, and games on small image display elements such as liquid crystal display elements and EL display elements, and displaying the displayed two-dimensional image As an observation object, use the eyepiece system as a virtual image to magnify and observe.

The eyepiece system is often used by attaching it to the observer's head or face, and it is preferable to be lightweight and compact.

Conventionally, it is known that an eyepiece system can be configured light-weight and compact with as few as four lenses.

In conventionally known eyepiece systems, the telecentricity on the object side is low.

When observing a two-dimensional image displayed on a liquid crystal display element, an organic EL display element, etc., or an image of an observation target part formed on the object-side end surface of an endoscope fiber bundle through the eyepiece system, the telecentricity on the object side is low, This results in differences in brightness or color depending on the viewing angle, making it difficult to obtain a high-definition observation image well.

Recently, high resolution is required for magnified virtual images observed with endoscopes, video content such as movies and games, and it is necessary to seek good correction of aberrations in the eyepiece system.

prior art literature

patent documents

Patent Document 1: Japanese Patent Application Laid-Open No. 11-23984

Contents of the invention

The problem to be solved by the invention

The problem to be solved by the present invention is to realize an eyepiece system that has good telecentricity on the object side and can perform good aberration correction, and an image observation device using the same.

means of solving problems

1. The eyepiece system is an eyepiece system that enlarges and forms the image of the observed object as a virtual image, and has the following characteristics. That is, the eyepiece system is configured by including a first group having a negative refractive power arranged on the object side, and a second group having a positive refractive power arranged on the eyeball side of the first group. The first group is a cemented lens of biconcave and biconvex lenses, and the second group consists of two or three positive lenses.

The object side is telecentric, the focal distance F (>0) of the whole system, the focal distance F1 (<0) of the first group, and the focal distance F2 (>0) of the second group satisfy the following conditions (1), ( 2).

(1) -5<Fl/F<-1

(2) 0.5<F2/F<3

2. In the eyepiece system of 1 above, on the image display element side of the first group, a positive meniscus lens with a concave surface facing the object side and two aspherical surfaces can be additionally arranged as a field curvature correction lens.

3. An image observation device, which is an image observation device for magnifying and observing a virtual image of a two-dimensionally displayed image, characterized in that the eyepiece system of 1 or 2 above is used as an optical system for forming the virtual image of the image.

4. The image observation device of the above 3 can be a head-mounted image observation device using an image display device for displaying a two-dimensional image and the eyepiece system of the above 1 or 2.

Supplementary note:

Conditions (1) and (2) are conditions for determining an appropriate range of the refractive power of the first group and the second group with respect to the refractive power of the entire system of the eyepiece system.

The first group has negative refractive power, so it has the effect of diverging the light from the observed object to the side of the eyeball.

By making the first group have such a diverging effect, the viewing angle can be expanded even when observing a small observation object, and the observation object can be formed into a magnified virtual image with a wide viewing angle, and the magnified virtual image becomes easy to observe.

The smaller the absolute value of the parameter Fl/F in the condition (1), the stronger the negative refractive power of the first group, and the greater the effect of diverging the object light to the eyeball side, but when the lower limit of the condition (1) is exceeded, the above-mentioned divergence effect becomes smaller. If it is too large, it is necessary to increase the "lens diameter" of the second group that collects the light beam from the observed object to the eyeball, which has the disadvantage of increasing the size of the entire eyepiece system and increasing the cost. In addition, it is difficult to secure telecentricity on the object side.

When the upper limit of the condition (1) is exceeded, the diverging effect becomes insufficient, and to realize, for example, a horizontal viewing angle of 40° to 45° as an easy-to-observe range, it is necessary to make the second group have a large positive refractive power. The increase of the positive refractive power of the second group tends to produce aberrations, and their correction becomes difficult.

The second group has positive refractive power, so that the light beams imparted with a tendency to diverge by the first group converge toward the eyeball.

From the viewpoint of aberration correction, it is difficult to constitute the second group with one positive lens, and it is preferable to use two to three positive lenses as described above to distribute the aberration correction function to them.

The smaller the parameter F2/F of the condition (2), the greater the positive refractive power of the second group. When the lower limit of the condition (4) is exceeded, the positive refractive power becomes excessive, and large aberrations are likely to occur, and the aberration correction becomes difficult.

When the upper limit of condition (2) is exceeded, the positive refractive power of the second group is somewhat insufficient, and the distance between the eyepiece system and the eyeball tends to be narrowed, making it difficult to realize the horizontal viewing angle of 40° to 45° as an easy-to-observe range.

The effect of the invention

As described above, according to the present invention, a new eyepiece system and an image observation device can be realized.

As described above, the eyepiece system has good telecentricity on the object side, and the brightness or color of the observed image does not vary depending on the viewing angle. As in the embodiments described later, a magnified virtual image with good performance and high definition can be obtained.

In addition, as in the eyepiece system of the above-mentioned 2, by additionally disposing a field curvature correction lens on the image display element side of the first group, even when the magnified virtual image to be observed becomes larger, the distortion of the image caused by field curvature can be effectively reduced. out of shape.

Description of drawings

FIG. 1 is a diagram showing a lens configuration of an eyepiece system of Embodiment 1. FIG.

FIG. 2 is a diagram showing a lens configuration of an eyepiece system of Embodiment 2. FIG.

FIG. 3 is a diagram showing a lens structure of an eyepiece system of Embodiment 3. FIG.

FIG. 4 is a diagram illustrating an embodiment of an image observation device.

FIG. 5( a ) is an aberration diagram of Example 1. FIG.

FIG. 5( b ) is an aberration diagram of Example 1. FIG.

FIG. 6( a ) is an aberration diagram of Example 2. FIG.

FIG. 6( b ) is an aberration diagram of Example 2. FIG.

FIG. 7( a ) is an aberration diagram of Example 3. FIG.

FIG. 7( b ) is an aberration diagram of Example 3. FIG.

detailed description

Embodiments will be described below.

Figures 1 to 3 illustrate three embodiments of eyepiece systems. These eyepiece systems respectively correspond to the eyepieces of Examples 1 to 3 described later. The eyepiece systems of these embodiments assume that a two-dimensional image displayed on a liquid crystal display element, an organic EL display element, or the like (hereinafter referred to as an image display element) is observed as an observation object.

In order to avoid complexity, the symbols are unified in FIGS. 1 to 3 . That is, in FIGS. 1 to 3 , the left side of the drawing is "image display element side", the right side is "eyeball side", and the "image display surface of the image display element" is indicated by IS. The image is displayed as a two-dimensional image on the image display surface IS.

The first group is denoted by the symbol G1 and the second group is denoted by the symbol G2. In addition, the symbol E represents the pupil in the eyeball. In addition, the lenses constituting the eyepiece system are numbered from the image display surface IS side, and as shown in FIGS. 1 to 3 , they are lenses L1 to L6.

An eyepiece system according to an embodiment is shown in FIG. 1 , and is composed of four lenses L1 to L4 as shown in the figure. The two lenses L1 and L2 on the side of the image display surface IS constitute the first group G1 of negative refractive power.

The lens L1 is a "biconcave lens with a large curvature on the image display surface side", the lens L2 is a "biconvex lens", and these lenses L1 and L2 are joined to form a "cemented lens".

Lenses L3 and L4 constitute a second group G2 of positive refractive power. These lenses L3 and L4 are both positive lenses. The lens L3 is a positive meniscus lens with a convex surface facing the image display surface IS side, and the lens L4 is a biconvex lens. Both surfaces of the lens L4 are aspherical, and the curvature (negative) of the peripheral portion is opposite to the curvature (positive) near the optical axis in the surface on the image display surface IS side.

That is, by constituting the second group G2 with two lenses L3 and L4, the aberration correction function is dispersed among these lenses L3 and L4, and the both surfaces of the lens L4 on the most eyeball side are aspherical to perform distortion or curvature of field. Correction.

The eyepiece system of the embodiment is shown in FIG. 2 , and is composed of six lenses L1 to L6 as shown in the figure. The lens L1 closest to the image display surface IS side is a "positive meniscus lens with a concave surface facing the object side and both surfaces are aspherical", and is a "field curvature correction lens".

The field curvature correction lens L1 is a so-called "field flattener lens" that reduces field curvature and flattens the imaging surface of a virtual image, and its "power" is relatively weak.

The lenses L2, L3 following the lens L1 constitute the first group G1, and the three lenses L4, L5, L6 disposed on the eyeball side constitute the second group G2.

The lenses L2 and L3 constituting the first group G1 are cemented lenses cemented to each other. The lens L1 is a biconcave lens with a large curvature on the image display surface IS side, and the lens L2 is a biconvex lens.

The three lenses L4, L5, and L6 constituting the second group G2 are all positive lenses. The lens L4 is a positive meniscus lens with the concave surface facing the image display surface IS side, the lens L5 is a biconvex lens, and the lens L6 is a convex surface facing the image display surface. Positive meniscus lens on IS side. Both surfaces of lens L6 are aspherical.

The eyepiece system of the embodiment is shown in FIG. 3 , and is composed of five lenses L1 to L5 as shown in the figure. The lens L1 closest to the image display surface IS side has a concave surface facing the object side, is a positive meniscus lens whose both surfaces are aspherical, and is a field curvature correction lens. The field curvature correction lens L1 is a field-flattening lens, and is a relatively weak lens.

The two lenses L2, L3 following the lens L1 constitute the first group G1, and the two lenses L4, L5 disposed on the eyeball side constitute the second group G2.

The lenses L2 and L3 constituting the first group G1 are cemented lenses cemented to each other, the lens L1 is a biconcave lens with a large curvature on the image display surface side, and the lens L2 is a biconvex lens.

The lenses L4 and L5 constituting the second group G2 are both positive lenses, the lens L4 is a biconvex lens, and the lens L5 is also a biconvex lens. Both surfaces of the lens L5 are aspherical.

FIG. 4 shows one form of a head-mounted image observation device using the eyepiece system as one form of use of the eyepiece system. In FIG. 4 , reference numeral 10 denotes an image observation device, and reference numeral 20 denotes an observer's head.

In the image observation device 10 , eyepiece systems 11L, 11R and image display elements 12L, 12R, which are main parts thereof, are housed in a casing 13 with a predetermined positional relationship. Furthermore, the casing 13 is attached to the observer's head 20 by an appropriate attachment method such as a belt or a frame.

The eyepiece system 11L and the image display element 12L are for the left eye, and the eyepiece 11R and the image display element 12R are for the right eye. As the eyepiece systems 11L and 11R, the devices described in 1 or 2 above, specifically, the devices described in Examples 1 to 3 described later are used.

As the image display elements 12L, 12R, a liquid crystal display element, an EL display element, etc. are used, and the image displayed as a two-dimensional image in these is an observation object with respect to the eyepiece system 11L, 11R.

Example

Hereinafter, three specific examples will be described.

In Examples 1 to 3 listed below, the surface number is the number of the lens surface counted from the object side, R represents the radius of curvature of each lens surface, and D represents the distance between adjacent lens surfaces. N represents the refractive index of the d-line of the lens material, and v represents the Abbe number.

In addition, the aspherical surface is represented by the following well-known formula.

X=(H ² /R)/[1+(1-k(H/r) ² } ^1/2 ]

+A·H ⁴ +B·H ⁶ +C·H ⁸ +D·H ¹⁰ +E·H ¹² …

In this formula, X is the displacement in the direction of the optical axis at the height H from the optical axis based on the vertex of the surface, k is the conic coefficient, A~E... are high-order aspheric coefficients, and R is the approximate Shaft radius of curvature. In addition, the unit of the quantity with reference to the length is mm.

Example 1

Example 1 is a specific example of the eyepiece system of the embodiment described with reference to FIG. 1 . Table 1 shows lens data of Example 1, and Table 2 shows aspherical surface data.

Table 1

face number R D. N v Remark 1 8.0 2 -17.6 1.0 1.9 19 3 26.3 8.3 1.8 43 4 -31.0 0.2 5 35.9 4.5 1.8 45 6 171.5 0.2 7 18.5 9.6 1.5 56 Aspherical 8 -37.5 24.0 Aspherical 9 Pupil (Φ9)

Table 2

Aspheric coefficient K A B C D. 7 -1.7 2.2E-05 -1.6E-07 1.1E-10 -1.2E-12 8 3.4 6.9E-05 -3.6E-07 8.6E-10 -1.1E-12

In addition, in the display of an aspheric surface, for example, "1.6.E-04" means "1.6×10 ^-4 ". The same applies to other examples.

In the eyepiece system of Embodiment 1, the focal length of the entire system is F=19.2 mm, the focal length of the first group G1 is F1=-46.8 mm, and the focal length of the second group is F2=27.6 mm. Therefore, the parameter F1/F=-2.4 of the condition (1), and the parameter F2/F=1.4 of the condition (2).

The diameter of the pupil E is 9mm, the eye relief (the distance between the lens surface closest to the eyeball and the eyeball (pupil)) is 24mm, the viewing distance of the virtual image is 10m, and the horizontal viewing angle is 45 degrees.

Therefore, when the eyepiece system of Example 1 is used as the eyepiece systems 11L, 11R in the image observation device of FIG. The position at an observation distance of 10m overlaps with the observation image.

The eyepiece system of Example 1 is a type in which the pupil diameter is 9 mm, which is large, and the axial resolution is emphasized.

FIG. 5 shows an aberration diagram related to the eyepiece system of Example 1. As shown in FIG. FIG. 5( a ) shows longitudinal aberration, and FIG. 5( b ) shows lateral aberration.

In the aberration diagram, R represents light with a wavelength of 629 nm, G represents light with a wavelength of 538 nm, and B represents light with a wavelength of 458 nm. The same applies to the aberration diagrams of the following examples.

Example 2

Example 2 is a specific example of the eyepiece system according to the embodiment described with reference to FIG. 2 . Table 3 shows lens data of Example 2, and Table 4 shows aspherical surface data.

table 3

face number R D. N v refer to 1 0.2 2 0.5 1.5 64 cover glass 3 4.4 4 -7.0 2.5 1.5 56 Aspherical 5 -6.1 0.6 Aspherical 6 -13.1 2.5 1.9 19 7 100.0 8.0 1.9 41 8 -25.8 0.4 9 -102.9 5.2 1.6 63 10 -27.7 0.3 11 97.2 5.2 1.6 63 12 -49.6 0.5 13 34.7 3.0 1.5 56 Aspherical 14 57.6 25.0 Aspherical 15 Pupil (Φ4)

Table 4

Aspheric coefficient K A B C D. 4 -0.9 -3.9E-04 1.6E-05 -1.3E-07 5.3E-10 5 -0.9 -8.0E-05 5.9E-06 -2.9E-08 3.3E-10 13 1.9 4.8E-06 -6.2E-08 4.2E-11 -4.9E-13 14 -68.0 2.5E-06 1.6E-08 -3.0E-10 3.5E-13

In the eyepiece system of Example 2, the focal length of the entire system is F=19.0 mm, the focal length of the first group G1 is Fl=-43.1 mm, and the focal length of the second group is F2=24.2 mm. Therefore, the parameter F1/F=-2.3 of the condition (1), and the parameter of the condition (2): F2/F=1.3.

The diameter of the pupil E is 4mm, the exit pupil distance is 25mm, the observation distance of the virtual image is 10m, and the horizontal viewing angle is 45 degrees. When the eyepiece system of Embodiment 2 is used as the eyepiece systems 11L, 11R in the image observation device of FIG. Observe that the images overlap.

The eyepiece system of Example 2 is a type in which the pupil diameter is equal to 4mm, which is equal to the average value of normal pupils, and the reduction of the deterioration of the observed image due to the deviation/inclination of the pupil is more important than the axial resolution. .

FIG. 6 shows aberration diagrams related to the eyepiece system of Example 2. FIG. Fig. 6(a) shows longitudinal aberration, and Fig. 6(b) shows transverse aberration.

Example 3

Example 3 is a specific example of the eyepiece system according to the embodiment described with reference to FIG. 3 . Table 5 shows lens data of Example 3, and Table 6 shows aspherical surface data.

table 5

face number R D. N v Remark 1 0.2 2 0.7 1.5 64 cover glass 3 3.8 4 -9.4 2.9 1.5 56 Aspherical 5 -7.3 0.6 Aspherical 6 -13.1 3.0 1.9 19 7 52.3 9.3 1.9 41 8 -23.9 0.4 9 70.9 8.0 1.7 50 10 -45.7 0.4

11 91.9 5.2 1.5 56 Aspherical 12 -69.5 25.0 Aspherical 13 Pupil (Φ4)

Table 6

Aspheric coefficient K A B C D. E. 4 -5.0 1.6.E-04 -1.3.E-05 1.6.E-07 -3.2.E-10 5 -0.7 4.2.E-04 -5.1.E-06 -5.2.E-09 6.6.E-10 11 7.6 8.4.E-06 -4.5.E-08 2.9.E-10 -8.4.E-13 1.1. E-15 12 3.6 -4.5.E-06 6.4.E-08 -1.2.E-10 -9.6.E-15 3.9.E-16

In the eyepiece system of Example 3, the focal length of the entire system is F=18.9mm, the focal length of the first group G1 is Fl=-55.0mm, and the focal length of the second group is F2=26.9mm. Therefore, the parameter F1/F=-2.9 of the condition (3), and the parameter F2/F=1.4 of the condition (4).

The diameter of the pupil E is 4 mm, the exit pupil distance is 25 mm, the observation distance of the virtual image is 10 m, and the horizontal viewing angle is 45 degrees.

When the eyepiece system of Embodiment 3 is used as the eyepiece systems 11L, 11R in the image observation device of FIG. Observe that the images overlap.

The eyepiece system of Example 3 is also a type in which the pupil diameter is equal to 4mm, which is equal to the average value of normal pupils, and the reduction of the observed image degradation caused by the shift/inclination of the pupil is more important than the axial resolution. , the deterioration of the observed image caused by the shift/inclination of the pupil is further reduced compared to Example 2.

FIG. 7 shows aberration diagrams related to the eyepiece system of Example 3. FIG. FIG. 7( a ) shows longitudinal aberration, and FIG. 7( b ) shows lateral aberration.

The various aberrations of the eyepiece systems of Examples 1 to 3 were well corrected and had good performance.

The lens L1 of the eyepiece closest to the image display surface IS in Examples 2 and 3 has a concave surface facing the object side, is a positive meniscus lens with both aspherical surfaces, and is a field curvature correction lens. Due to the presence of the field curvature correcting lens L1, it can be seen that astigmatism and image surface curvature are corrected more effectively than in the eyepiece system of Example 1.

The eyepiece system with good telecentricity on the object side, good performance, and high-definition magnified virtual image can realize that the brightness or color of the observed image does not change depending on the viewing angle in head-mounted image observation devices. observation image.

Symbol Description

G1, the first group G2, the second group

18. Image display surface E, pupil

10. Image observation device 11L, 11R, eyepiece system

12L, 12R, image display components

Claims (3)

1. A kind of eyepiece system, is used for the image of observing object as virtual image magnification imaging, and described eyepiece system is characterized in that, The eyepiece system has a first group with negative refractive power arranged on the object side and a second group with positive refractive power arranged on the eyeball side of the first group, The first group is the cemented lens of biconcave lens and biconvex lens, The second group consists of three positive lenses, which are, in order from the object side, a positive meniscus lens with a concave surface facing the image display surface IS side, a biconvex lens, and a positive curved lens with a convex surface facing the image display surface IS side. moon lens, On the object side of the first group, a positive meniscus lens with a concave surface facing the image display element side and two aspheric surfaces is additionally arranged as an image surface curvature correction lens, The object side is telecentric, The focal distance F of the entire system, the focal distance F1 of the first group, and the focal distance F2 of the second group meet the conditions: (1)-5<Fl/F<-1 (2) 0.5<F2/F<3 Wherein, F>0, F1<0, F2>0. 2. An image observation device, which is a two-dimensionally displayed image, an image observation device for magnifying and observing a virtual image, characterized in that, The eyepiece system of claim 1 is used as an optical system for forming a virtual image of said image. 3. The image observation device according to claim 2, wherein, The image observation device is a head-mounted image observation device using an image display element that displays a two-dimensional image and the eyepiece system described in claim 1 .